Content Marketing is all about creating good, original content that can be used to attract and convert prospective customers. This content usually is offered for free on the web and is likely to be transmitted through social media sites, feeds or blogs.
Content marketing is all about relevance i.e. relevant information that users will appreciate and take the time to read. This information is highly targeted, educational and closely related to the products that the author is offering. An objective of Content Marketing is usually to form a connection with the reader (that eventually may lead to a sale), this is very different from Spam type marketing where the only objective is to target as many people as possible in the hope that some of these will buy the product.